CBQE-703 Add tests for different document key types

Change-Id: I7a7abfe415ee002ac54de91a51312bf5f520890d
Reviewed-on: http://review.couchbase.org/25858
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Iryna Mironava <irynamironava@yandex.ru>